package cn.myzqu.sign.user.server.utils;

import java.security.MessageDigest;

public class MD5Util {
	/** 十六进制下数字到字符的映射数组 */
    private final static String[] hexDigits = { "0", "1", "2", "3", "4", "5",
            "6", "7", "8", "9", "a", "b", "c", "d", "e", "f" };

/**
     * 对字符串进行MD5编码
     * @param originString
     * @return
     */
	public static String encodeByMD5(String originString) {
        if (originString != null){
        	StringBuffer stringBuffer = new StringBuffer();
        	stringBuffer.append(originString);
        	//BookSharingPlatform  MD5加密后的32位数字作为秘钥
        	stringBuffer.append("FF553D194F2D3CE080D822AFB4124290");
        	//加入秘钥后的字符串在进行MD5加密
        	originString = String.valueOf(stringBuffer);
            try {
                MessageDigest md = MessageDigest.getInstance("MD5");
                byte[] results = md.digest(originString .getBytes());
                String resultString = byteArrayToHexString(results);
                return resultString.toUpperCase();
            } catch (Exception ex) {
                ex.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 转换字节数组为16进制字串
     * 
     * @param b  字节数组
     * @return 十六进制字串
     */
    private static String byteArrayToHexString(byte[] b) {
        StringBuffer resultSb = new StringBuffer();
        for (int i = 0; i < b.length; i++) {
            resultSb.append(byteToHexString(b[i]));
        }
        return resultSb.toString();
    }

    /**
     * 将一个字节转化成16进制形式的字符串
     * @param b
     * @return
     */
    private static String byteToHexString(byte b) {
        int n = b;
        if (n < 0)
        {   n = 256 + n;}
        int d1 = n / 16;
        int d2 = n % 16;
        return hexDigits[d1] + hexDigits[d2];
    }
}
